High ISO Compared: Sony A7S vs. A7R vs. Canon EOS 5D III

Introduction

Sony's A7-series lineup has garnered quite a lot of interest amongst camera enthusiasts, striking an appealing balance between image quality and size. Both the A7 and A7R bodies, as well as the native FE lenses Sony has recently introduced, are remarkably small and lightweight - especially when you consider the quality of images they're capable of producing.

The A7S is Sony's newest entry in its full-frame mirrorless lineup. But where the 'R' in A7R stood for resolution, the 'S' in the 12MP A7S stands for sensitivity. Furthermore, with its full-sensor readout and 4K video capabilities, the A7S is as much a camera for video as it is a camera for stills. And let's face it: there are very few videographers and photographers who wouldn't be thrilled by a camera offering higher sensitivity and impressive, low noise, high ISO performance.

Now, this purported increase in sensitivity comes at a cost: in the face of cameras with ever-increasing megapixels, the A7S comes in at a rather paltry 12MP. Lower resolution and higher sensitivity are certainly not unheard of - the Canon 1DX and Nikon D4S both top out at relatively modest resolutions of 18 MP and 16MP, respectively (though this is partly done in the name of speed). But is the resolution of a bygone era (Canon EOS 5D anyone?) a worthy tradeoff for the still image and video quality enhancements? Sony certainly seems to think so.

We just got our hands on an A7S, and have been busy putting it up against its competitors to see what advantages it offers and, quite frankly, to see if the claims regarding its low light performance are accurate. Particularly, some of us here have been curious as to whether not the increased ISO performance is significant enough to warrant the resolution tradeoff when the A7S is put up against its older sibling - the A7R.

Why make this resolution trade-off at all? Leaving aside video considerations (such as simplifying full sensor readout) for now, lower resolution sensors can increase pixel-level performance (because bigger pixels capture more light), but it's typically total light gathering area across the entire sensor that is a major determinant of ISO performance, all else being equal. So, to see whether the A7S offers anything beyond the pixel-level benefit its lower resolution would lead you to expect, the higher resolution image is normalized to the resolution of the lower resolution camera. Ultimately, for the A7S to make sense to stills as well as video shooters, Sony's engineers need to have exploited some of the other advantages that well-designed larger pixels can potentially bring *1.

The Shootout

We put the A7S up against the higher resolution A7R to see if the A7S offered any significant high ISO advantages over the A7R when the output of the A7R was downsized to that of the A7S. Furthermore, we pitted the A7S against a professional DSLR not too far outside the price range of the A7S. And so, we bring you this real-world comparison between the Sony A7S, Sony A7R, and Canon EOS 5D Mark III.

We shot a night scene that included a range of tones from deep shadows to bright highlights to get a comprehensive idea of noise performance of these cameras at various ISOs.

We waited until midnight to ensure minimal changes in ambient light during the course of our shoot (summer days are long in Seattle). In order to level the playing field for all three the cameras we did a few things:

Used the same lens (Canon 24-70 f/4L IS) for all cameras. A Metabones Smart Adapter III was used to fit the Canon lens on to the Sony bodies.

Aperture and shutter speed were matched across all cameras for any particular ISO setting.

RAW files were converted in ACR 8.5 to give relatively consistent rendering across cameras. This was done by manually selecting white balance per camera, and adjusting Shadow Tint as necessary at higher ISOs in order to avoid magenta-tinted blacks. Sharpening and noise reduction were left to ACR defaults (Sharpening: 25 | Luminance NR: 0 | Color NR: 25).

Since the A7R and 5D Mark III don't offer ISO sensitivity settings above 25,600 and 102,400, respectively, these higher ISO shots were simulated by maxing out the ISO on each respective camera, adjusting shutter speed, and then digitally boosting exposure in ACR to aid comparisons against the higher ISOs of compared cameras.

Do note, however, that (1) nobody in their right mind would boost high ISO JPEGs in this manner (it's preferable to digitally boost Raws over JPEGs), and (2) when we did boost the high ISO Raw files in ACR, significant noise resulted. This itself speaks to the value of the higher ISO modes on the A7S (if you need them, that is), but also indicates that a more careful balancing act of noise reduction, sharpening, and exposure boosting would be more appropriate to obtain the 'simulated' higher ISO values than by simple (digital) exposure boosting.

Without further ado, let's get to the comparisons. Below and on the next page you'll find a variant of our typical studio scene widget. Have a play with it (further instructions after the widget), then view some of our specific thoughts on the comparison on the next page. By default we've set the widget below to compare the A7S vs A7R, but you can compare either camera to the Canon EOS 5D Mark III as well. And, as always, all files are available for download if you would like to tinker yourself.

Using the Widget

The widget above and on the next page is a variant of our typical studio scene widget. At the top is a drop down menu that allows you to select 'Normalized (12 MP)' or 'Native Resolution'. 'Native Resolution' indicates that images retain the maximum resolution the camera is capable of, whereas for the normalized analysis, images were downsized to 12 MP (using the bicubic resampling method).

As usual, we also have the Full, Print, and Web buttons at the top right of the widget. Full will maintain whatever you've selected in the top, center drop-down menu (12 MP for the normalized analysis, and full sensor resolution for the native resolution analysis). Print will downsize all images to 8 MP, while Web downsizes all images to 5 MP.

Remember that although the widget above starts with the Sony A7S pitted against the A7R, you can also compare the Canon 5D Mark III against either camera by selecting it in either drop-down menu.

Footnotes:

*1 For example, lowering cumulative sensor read noise, increasing effective sensor efficiency, and other factors that - to prevent this article sprawling - we won't elaborate upon further here.

Comments

There’s a pretty big Sony vs. Canon question in what color those arches bait up and left of center look to the human eye. Sony has them white and a bit blown out. Canon has them warm and detailed. If they are cream or yellow to the human eye then Sony is screwing up. If not, Canon is screwing up. It’s not like it’s a small difference.

If the arches were turned on it makes sense. It’s not the Adobe RAW calibration because it happens in the JPEGs. In addition to the arches and the windows under the crane, the rendering is different in the crosswalk in the foreground.

None of those cameras are particularly useful beyond ISO 6400, and until that point A7s is behind everybody else. Going at higher ISO it looks like A7s is cooking its raw, but it's of little use for anybody but videographers.

You cannot cook the raw to extract detail that isn't there in the first place. Otherwise you'd be able to take the A7r or 5DIII raw file and cook it yourself until you get the detail the A7s is offering.

I agree with noirdesir re. "cooking" the raw files (if the detail was there for the Canon, it would come out in the post-processing).

But forpetessake's point remains: you're not going to use stills from any of these cameras with ISO above 6400 for anything that matters (or at most 12800 for small web sizes). The quality is too poor. And up to that point the 5DIII more than holds its own. The differences in the system, especially lenses, are going to matter much more, and leave the 5D with a massive advantage.

For videographers the GH4 is, in my opinion, a much better camera, and has a much better system around it (lenses!) The A7s only has a niche in videographers that would occasionally benefit from being able to film in extreme low light (which is probably a non-trivial niche, so I think there is a legitimate market for this camera) and are willing to work with adapters to use lenses made for other mounts when needed (e.g., Canon 24/1.4 vs. Sony 24/1.4 is a 1 stop advantage...)

@noirdesir: you know that the camera is cooking its raw when you see the DR curve crossing the one for the ideal (noiseless) sensor. Why it doesn't work that well in PP? -- It's a good question. But it's not the first case: take Fuji cooked raws and try to get the same from the same sensor in NEX5/6 in PP, and you'll face the same problem.

I still have my original Canon 5D, 12mp and all, that made me a lot of money doing weddings, and making a LOT of brides happy. If you want to take a wedding of a women with a 36mp or more camera have at it.

But I can see if you are into landscape or fine art photography have at it. I can not deny if I had a camera years ago that could shoot at 6400 iso I would have been a happy camper. There was a reason that people made flashes lol years ago. Not the most becoming to a bride also. So this just proves , just like it was years ago, no ONE camera can do it all if you want to make a living out of it. And not even as a hobby if you have the money to make it happen. So study up from shots from the past, which now like look they were taken with dinosaur cameras, and enjoy the outcome. It can be a VERY rewarding hobby or profession.

I often think these reviews prove how subjective this kind of pixel peeping is. Personally having looked at the comparison I'd say there isn't a huge amount of difference, certainly not enough to claim you'd be an idiot for buying one over another if you wanted a camera that was good at higher ISO.

For me personally the A7S is the cleaner of the 3 cameras the higher ISO that you go, but there's not a lot in it. I accept in saying this that I'm both being entirely subjective, as in I have no quantitative way of saying why I hold this opinion other than they're my eyes I'm looking through and its my own personal taste. I also accept fully that some of you may have far better taste than me :-).

DPR - these tests would be fascinating if you removed the brands and had to guess which camera was which from the images - it would generate a lot of clicks and hopefully good debate and also prove once and for all how subjective this is.

The differences from 102400 and up are striking. Obviously this isn't where a lot of people will be using the cameras, but to say there's "not a lot in it" I can only assume you've not looked at the highest ISOs.

@mgrum you assume wrong, I did. Perhaps if I explain a little more. I regard high iso as anything 6400 and above, for me 102400 and above is the extreme end of the high iso scale. If I'm looking to buy a camera for high Iso shooting (which I'm assuming this test is designed to help) I'm going to look at all the high ISO's i'm going to use, chances are like with most photographs I'll try and get the ISO as low as possible irrespective of the conditions. If you look through all the high-iso shots (based admittedly on my definition) then on balance there isn't a lot in it, certainly at 6400 to 51200 I'd argue the A7r retains more detail and better colour than the A7S, however as I did say in my initial comment the higher ISO that you go the cleaner the A7s gets and pulls away. So my comment is really one of balance across high-ISO not just the really high end which I agree with you on. All my own opines of course,

@RichRMA: This is what you would expect. Majority of people buying a 5DIII would already be canon users and just upgrading to the latest and greatest body. There is a very high chance that they will hold on to that camera. A person buying the A7r on the other hand is basically trying out a brand new system to see if they like it. A retention rate of 4 out of 5 is remarkably high for that. I suspect the actual retention rate will be lower, and the poll is skewed because those who currently own the camera are more likely to take part in the poll.

in full size view, 25600 is not even useable anymore. The tests shots I downed in full size at imaging resource show that A7S starts noising at 3200 ISO, just like all other FF sensors. The only factor that plays here is until where the noise can be mastered by soft ware and where does noise takes it over. I have cleaned a A7S 80000 iso shot and got a perfect useable shot, the only thing is that the resolution looks like my D40, and there is no mystery about that, it is the same pixel pitch and higher than 12500 iso, it has no dynamic advantage anymore. Simply, we gain on one side what we sacrifice on the other. Bigger pixels and less pixel count kill resolution, smaller pixels and higher pixel count kills sensitivity. All is to know what one wants and when I see A7R noise compared to A7S noise at 25000 ISO, I see no reason to buy the smaller pixel count camera. The difference between 7 and 7R is not that much visible, both perform almost the same, 7S is a world back here.

Although I expected better results from the A7s, I keep in mind that this is a camera designed mostly for videographers, and this is where its low light performance should be more evident. Of course I will have to wait to see some proper comparison videos before I come to any conclusions.

It doesn't invalidate the test, because in real world use you'd be downsampling for print or screen display anyways. So, how the Sony image looks when downsampled to the Canon's level is perfectly valid, and gives you a far more *practical* comparison than to compare them only at their native resolutions.

No in real world I would not be downsampling for printing. More likely upsampling. If I decided to print at 300DPI for example I would be printing at that size or smaller. The proper way to compare noise is not pixel peaking. The proper way is to use full resolution and to print to the size camera allows.

On a different note either 5D III is underexposed or Sonys are overexposed. Just position marque over arches in the back and they are not the same. Overexposed for Sony and looks good for Canon. That in itself invalidates the test.

Size is irrelevant. Take your camera and take a picture at 25600 ISO and look at rear LCD. You know your photo is really noisy but it does not look like on 3 inch LCD unless you zoom in.So as the saying goes "What is good for a Goose is good for a Gander" That means if you choose to print at 300DPI to a max allowed size of the higher resolution camera you would have to print lower resolution camera to the same size thus you will see more noise.As far as exposure posted, those are numbers only. The actual exposure would have to be equalized. For example Nikon D600/610 and D800 is about 1/2 stop overexposed than Canon 5D III even if settings are the same.There was thread on that. I verified it myself because I had 5D III and D800.

Your assumptions are just as invalid when you hold it to 300 DPI print at 36MP. That's why I said depends on print size. I don't print large, personally. So this is very relevant. I shoot my Canon on mRAW. I wouldn't ever use a 36MP or 24MP image full size, so this is exactly what I'd rather see.

To be honest, more realistic for me would be normalizing at 8MP. Never have needed more resolution that the old 30D I used to have.

The 300DPI is just a number. It could be 200. It doesn't matter.The argument here is about noise. If they compared two cameras with identical resolution I would not have a problem with it. I shoot D800e at higher ISO than I was shooting 5D2/5D3 because even though I know noise per pixel is not any better but shear amount of pixels hides the noise. Just like smaller size LCD hides the noise. More pixels equal less noise per given print size.Let me explain this better:For example:Lets say I can print 8x10 at the certain high ISO from lower resolution camera at the point that I just starting to see minor noise. But if I print the same size from the higher resolution camera at the same ISO I would not see noise at all. I would have to print larger lets say 9x12 to start seeing the noise. The only stipulation is that per pixel noise performance has to be equal from both cameras at the same ISO but in reality, if I print 5D3 to 8x10 I can print D800e to 12x18 with equal results.

It is not a theory, it is a fact!!!! You can easily prove it to yourself even from samples you can download from here.Do you have a printer?You don't even need a printer, you can do it on the screen in Photoshop.If you make identical size panes (not by magnification) you can see it for yourself.

i'll hbet that as always panasonich gh4 apart high iso will produce better video than sony...so far sony has never been top in the list of videographers, due to frame rate codec rolling shutter...will see all these issue, much more important than simply low light.

The Canon does a good job of staying close to the Sony 7s, so does the 7R. The camera seems to have a very narrow use. I think Sony should have made a more conventional camera, used 16-18MP. Still a low light leader, with a more useful rate of MPs.

I for one am disappointed by the performance of the A7S. 52,000 ISO is "moderately high"?Can we please get real?What I was hoping for was clas-leading stills up to 6,400 or 10,000. Who on earth needs higher? Instead, it seems you lose a lot of resolution for littel practical advantage.

Haha, well I used the term 'extremely high' for ISO 204k and above, so I figured 'moderately high' sounded better than 'less extremely high'. :)

As for 'class leading stills up to 6400...' - they probably are. It's just that 'class leading' here is not much much better than '2nd best'. Why? Because sensor performance has already evolved to a point where they're largely shot noise limited. And that's noise in the light itself - not much you can do about that besides capture more light.

@Rishi sensor efficiency is already hitting 50% in some cases so there only around 1 stop more improvement to be had. There will be no more big jumps in ISO performance (unless you count 1 stop as a big jump).

we're pretty much in the golden age of photography when it comes to low light performance. Film photographers who regularly shot ISO 50 and ISO 25 film would have scarcely been able to imagine ISO 409,600

There's something which doesn't add up in these tests. When comparing the image crops against the same scene shot with the 5dmkIII the sony blows out the white structure (very little detail) and the interior part of the building is likewise blown out. In contrast the 5dmkIII preserves the detail in both areas. Is this a DR issue or something to do with exposure?

You are forgetting fan boys. They will jump on the slightest piece of evidence and blow it up to a unshakeable reality. Doesn't matter it is easily falsified, the other fan boys will like it to the top.

You seem to be confusing the images. The two displayed are the 7R and 7S. Dial in the 5dmkIII and my comments still stand. The lights are off in the 5dmkIII version in the main part of the building and yet the 5dmkIII exposure appears different with better detail preservation in the white structure and the upper lights in the building are not blown out.

What you forgot to mention is that the 5D has vastly superior dynamic range in all shots. The highlights in the sony raws are all blown out while the canon retains considerably more detail.

BTW I own a 5d III and a Sony A7 (non-r). The canon consistantly delivers less noise and better dynamic range at all isos above 400. The exception being at iso 100 and iso200 where the sony has less shadow noise if you need to lift the shadows dramatically.

To complete this: Any test site (hint: DXO) rating the canon sensor far below the sony sensor, should start using their cameras to take photos instead of performing absurd measurebating tests which do not translate into real life.

Canon DSLR have bad DR compared to Nikon since 2007 - the D3 came to market. Check out DxOMark, their own Sensors aren't winning a flower pot against the Nikon & Sony competition in terms of DR, color depth & lowlight score. Even Canons 1DX is a Joke compared to the D4S.

And the worst thing for sure - the same old Sensor (18MP) from EOS 550D to the latest Beginner EOS 1200D, and all between, 600D, 650D, 700D, 100D....no advantage in newer iterations.

there is something weird going on about the highlights coming off these images, the A7R / A7S are consistently blowing out some areas versus the 5D shot. maybe highlight headroom - versus the sony which has better shadow detail. and lol @ marc.. world doesn't revolve around a test site that uses faulty measurements and certainly doesn't publish "how" they do it.

People still don't seem to understand that highlight headroom in RAW tells you little about DR, more about metering or how the manufacturer and RAW developers respectively decided to implement metering compared to middle gray plus saturation poit and the default gamma curve.

DR is mostly defined by the shadow range (see also the DXO explanations), highlight range is usually a choice of exposure (relative to the saturation point of the sensor).

You are absolutely right about DXO sensor scores. It took me a while to figure out why, and I thought I was wrong for 5 minutes, but that end score number is based on other numbers you can dig up on the DXOMark website.

The most interesting data on the sensors seems to be called the "Full CS", however when you read the fine print you discover the charts are based on a theoretical light source, not testing with a real light source.

It's often the case that DXO completely misuses the term "measurements" in its "testing" results displayed. They're not measurements; they're ideas about what should be with limited givens, i.e. models. So not really "testing" either.

No wonder that DXO doesn't account for the lenses used in determining the sensor score; reality would disturb theory.

I am curious to know whether matching the shutter speed for each ISO played a part there? One possible explanation could be that the sonys are more sensitive for each ISO such that when the shutter speeds are matched across all three cameras, sonys result in blown highlights.

Most blown highlights look similar on both cameras, but the white arches on the upper left side of the building in the middle do have creamy color in Canon, while totally white in Sony pic. Also, the yellow object inside the building in the middle has deeper color with Canon than with Sony. Of course that is, if lighting has been similar on all shots and is not varying.

Too much time is wasted on comparing ridiculously high iso ratings that make up such a minute amount of where photographers normally reside. There must be a small underground movement of people producing 20x30 landscape, street, or portraiture at 100,000 iso that I must be missing.

I rarely go into the 32-6400 range but years ago I rarely went to 1600. At sane sizes, these ranges look fine to me and my customers. Would I say no if the next version Canon put out let me delve a stop or two higher? I may not need them but I doubt I'd complain if decent noise and tonal ranges were improved.

This test convincingly demonstrates that unless you routinely shoot at ISO 25.6k or higher, don't purchase the A7S over the A7R b/c of its ISO performance.

We think that's somewhat valuable information to certain people.

I also, personally, found it interesting that these results suggest that it's not really sensor efficiency that was improved, but rather some element of electronic performance that is optimized for extremely low light light sensitivity in the A7S. Had it been the former, we would've seen ISO advantages even at lower ISOs from the greater amounts of light captured. This doesn't seem to be the case, though we'll have to verify this using some more controlled lab tests and SNR analyses.

At ISO 3200, the noise levels are more or less the same but the 5D3 and the A7R images have more detail. At ISO 6400 maybe - maybe, the A7S has some slight advantage. Above that, the shadow cast destroys the 5D3 and the A7R images.

Before talking about isos people should learn what a correct exposure is. I shoot iso400 film hand held at night with no tripod on a 55 years old film camera. Look at my results on my gallery (just night examples of what I do, me who is just an amateur).

400 ISO film? Not hard covering up flaws of a film that has the same resolution as a 3-4 megapixel digital sensor. Shooting hand-held at night at 1/4" second, no one will notice the slight motion blur either.

Go up into the Rocky Mountains to photograph wildflowers. Set up your RRS or Giottos tripod with your favorite camera and lens, compose and calculate exposure. Then notice that you'll need 1/4000 to 1/8000 sec to stop the fluttering flowers and leaves from the ever present wind. I forgot to mention that you are in the shade to get the deepest and richest colors and that some flowers only bloom in the shade such as the Lady Slipper Orchid or a Coloradian's favorite, the Columbine. The shadows are a good 8 EV darker than sunlight.

Of course multiple image HDR is impossible under 4,000 frames per second due to ghosting.

A beautifully clean ISO above 400K? I'd take out a second mortgage were it available. For now I'll keep saving my nickels for a D3S or D4S.

What puzzles me here, is why to compare the Sony models to EOS-5DMkIII, whereas we know that the EOS-6D and Nikon Df have both superior low light properties. Of course aside of the "pixel peeking" we also need to be able to focus in low light. As a EOS-6D user, I can only attest the amazing ability of this camera to focus, officially even in -3EV, albeit I have no scientific way to check if that value is really true. In a practical shootout in an Aquarium the EOS-5D was "hopelessly helpless", and that is that. So why to compare low light properties to an ultra expensive camera, aimed at a different application? In this context: note that the new Lumix GH4 focuses even in -4EV, a record nowadays, and a fact often overseen, because most people think of GH4 as a video tool.

While i don't want to be the captain obvious here, i would like to point out that better dark areas means that you can push the shadows up while maintaining a lower iso than competition, preserving highlights and using a faster shutter speed. Is much like the D-Lighting from Nikon, what i think is smarter than usual Sonys approach just pushing the shadows without choosing a lower iso."That been said" the real iso difference is greater than the comparison test has shown. I didn't downloaded and tested but i will guess a gain of 2/3 stops over the results here.

This model is really a video-centric DSLR release. ISO aside, this camera has wayyyy more recorded detail than the 5MKIII in video mode. Lets face it, the MKIII is just soft with h.264 video. RAW video is a different story, but the Sony will bring FF goodness with a video image on par with its still output. Very welcomed for video folks compared to Canon purposefully hobbling the MKIII on the video side.

If you do not shoot video then there is not a lot of reason to choose the A7s over other options.

1) Less pixels = less resolution = more prone to moire with very fine detail. Nyquist and such...

2) Lightroom's demosaicing algorithm isn't able to resolve very fine detail without producing labyrinth patterns. The latter are deliberately smeared away by LR, which in turn produces moire instead. Other raw converters might get away without the moire on the very same areas (Raw Therapee being one example).

Not far from what I expected to see for stills, but I am expecting to be amazed at low light video from the A7s.

If the low light video from the A7s does not produce the "holy-crap, wow!" effect, then I won't see any point to this camera, either A7r or 5DIII would be better options. The A7s video needs to be really clean and detailed up to ISO 25,000, and useable above that, in order for this camera to make sense. Otherwise why not take the A7r for a light weight camera, or the 5DIII for an all around work horse that natively accepts a ton of excellent lenses?

Indeed. But at least there is practical proof, that lower pixel amount at given area still means less noise at high ISO, while many people say otherwise, so If 24 is enaugh for you, be happy with 24 and don´t go for 36 because of noise performance.... 12, well, it really is not much these days...

And yet the Nikon Df and D4s do indeed remain the best lowlight high ISO cameras, and they only have 16MP. And no the A7 and Canon 6D don't come real close to the Nikons' performance, perhaps the Canon 1DX though.

So in fact there is something to the equation of bigger pixels meaning better lowlight performance, since all of the best performing FF bodies in that respect have fewer than 20MP, however it looks like Nikon, Canon too, knows something Sony doesn't. So it's not that 12MP with the same vintage sensor is automatically better than 16MP in the same space.

If you like the A body system from Sony and want very very good lowlight high ISO performance, this is the body for you. If you want absolutely the best H-ISO lowlight performance, then that's the D4s likely.

I have the 6D and I'm happy with it. I'm aware that D4 and 1DX are better in high ISO. I was surprised that Sony did not manage to do better with 12MP today. It's almost 10 years that the 5D came out. Of course the A7S is a lot better at high ISO but it should still be a lot better. The pixels are almost 2 times bigger than in the 5DmkIII which also came out a couple of years ago.

HowaboutRAW: your comment seems to indicate that the A7S should perform better if it 'knew about' the 'sensor data processing' CaNikon 'know about'.

It's not sensor data processing that's the issue here. It's the extremely low levels of light reaching the sensor at very high ISOs. There's no reason to believe a Canon or Nikon would do any better, barring drastic increases in sensor efficiencies (that we are currently unaware of).

DxOMark's Full SNR curves for the Nikno D4S vs. the Sony A7S tell a different story - the A7S has higher SNR for any grey value than the D4S at the same ISO. Granted these aren't normalized, so the 16 MP D4S curves will shift slightly to the left after normalization. But I'd be surprised if it'd shift far enough to overcome the A7S's ISO 409k curve crossing the x-axis (SNR = 1) at a grey value around where the D4S' ISO 204k curve hits SNR = 1.

Ostensibly, at the pixel level, that's a ~1 stop advantage for the A7S over the D4S at ISO 409k right there. Of course, that advantage will drop after normalization and/or for brighter tones.

But I'd find it hard to believe, from the empirical data, that it'd be worse - as you claim. If you have data/images that prove otherwise, please do share.

I'll see if I can get some normalized full SNR analyses together, and at some point I'll try adding the Nikon to the comparison.

This camera is Sony saying: Look we can do high ISO. At very high ISO the A7S is indeed better, but with the low resolution this seems to be a camera for a very small niche, or perhaps purely for bragging rights.

12MP, and big MPs at that, simply is not low resolution, unless you plan on printing posters. It's real easy to print at 12" x 18" with files from a 12MP sensor. Lens quality and noise control carry far more import than they're usually credited with.

Now if you want to use that 55mm lens on the Sony as a telephoto, right being able to crop down from 36MP helps. Or again if you want to print some $400 poster.

I take away two impressions from this comparison:- The Canon beats both cameras (just look at those arches in the back - or are they Klingon Birds of Prey?)- Stay away from high ISO if at all possible. Tripod anyone?

Those arches are blown out in the sony's and not in the Canon. Not a resolution difference but dynamic range or lighting. Since nothing else is blown out more in the sony's i guess the lighting around the arches was differrent during the canon-shoot.

Arches look like they had different lighting temperature/intensity between the 5DM3 and A7s shots - other highlights in the scene don't show the same disparity between the two cameras. And they're recoverable anyway - here is a 100% crop from both raws with the highlight recovery set to 100% in LR5 for both:

Seems strange for me, but in comparison with the Canon 5D Mark III, at not exceptionnaly high ISO, says ISO 6400, with matched exposure, the Canon have much more Dynamic Range, streets and lights are less "burned".

It's a mixed bag, with stellar performance on very high ISO, but underperforming in the dynamic range area at 6400 ISO or under, compared to Canon 5D Mark III, not even talking about resolution.

Perfect for very high ISO and poor performer elsewhere, it's a mixed bag...

Remember that dynamic range is the RATIO between saturation level and noise. At ISO 6400 the difference is not large, but at higher ISOs the A7s has obviously much better DR.

I agree that the A7s RAWs look slightly more saturated in bright yellows at ISO6400. However, it has less noise in shadows as well. By slightly turning down the exposure on the A7s and compensating in ACR/PP, results would become more similar for the two cameras at ISO6400.

I didn't miss that at all. Of course any camera can blow highlights. Where your too simplistic answer was wrong was in saying that "Blown highlights has nothing to do with DR." That's just as misguided as saying that a camera with 20 stops of DR can also blow highlights. If it does, it's just as much due to an incompetent photographer not using an appropriate exposure as putting prevention of blown highlights above all else when using a camera with such poor DR that shadow areas go black.

That this wouldn't be obvious to a wedding or portrait photographer that should know better is very odd.

Starting October 1st, Getty Images will no longer accept images in which the models have been Photoshopped to "look thinner or larger." The change was made due to a French law that requires disclosure of such images.

A court ruling our of Newton, Massachusetts has set an important legal precedent for drone pilots: federal drone laws will now trump local drone regulations in situations where the two are in conflict.

macOS High Sierra came out today, but if you use a Wacom tablet you need to wait a few weeks before you upgrade. According to Wacom, they won't have a compatible driver ready for you until "late October."

Vitec, the company that owns popular accessory maker Manfrotto, has just acquired JOBY and Lowepro for a cool $10.3 million in cash. The acquisition adds JOBY and Lowepro to Vitec's already sizable collection of camera gear brands.

A veteran photojournalist, Rick Wilking secured a spot in the path of totality for the August solar eclipse. While things didn't quite pan out as predicted, an unexpected subject in the sky and a quick reaction made for a once-in-a-lifetime shot.